Patent GB-711586-A (GB)
Title: Improvements in and relating to stabilised unvulcanised rubber
IPC: C08K5/39
Filed: 1950-07-07
Abstract: Tacky compositions contain 32 to 60 per cent. of rubber in its soft, hydrocarbon-soluble and unvulcanized state, 21 to 41 per cent. of a tacky resin compatible with the rubber, and as a stabilizer against change in the plastic properties of the compositions with lapse of time, 0.03 to 10 per cent., preferably 1 to 3 per cent., of a dithiocarbamate of formula: <FORM:0711586/IV (a)/1> wherein R is a saturated or unsaturated alkyl, aryl or amino-substituted alkyl or aryl group, R1 is hydrogen or an alkyl, aralkyl or alkamine group, or R and R1 is N-cycloalkyl, and M is Sb, Bi, Cd, Cu, Pb, Se, Na, Sn or Zn and n the valency of this metal.  The rubber component is exemplified by 1 part of polyisobutylene of mol. wt. 80,000-120,000 with 5 parts of natural raw rubber and 1 part of butadiene (76 per cent.)-styrene (24 per cent.) copolymer of Mooney value 66 with 2 parts of natural raw rubber.  The resin may be p-tert. amyl phenol-formaldehyde resin, hydrogenated rosin glyceride, dehydrogenated rosin, dehydrogenated rosin glyceride.  Other ingredients may be a liquid or waxy plasticizer such as lanolin, mineral oil or paraffin wax, a filler such as zinc oxide, titanium dioxide, calcium carbonate, clay, talc, hydrated aluminium silicate, carbon black, starch, and a standard antioxidant, e.g. phenyl beta naphthylamine, butylated polyhydroxyphenol or p-tert. amyl polyhydroxyphenol.  The compositions are used for application to backings in the preparation of pressure-sensitive adhesive tapes, as heat-sealing adhesives, and as shoemaker's cements.ALSO:Tacky compositions, especially pressure-sensitive adhesive compositions, contain 32 to 60 per cent. of rubber in its soft, hydrocarbon-soluble and unvulcanized state, 21 to 41 per cent. of a tacky resin compatible with the rubber and as a stabilizer against change in the plastic properties of the compositions with lapse of time, 0.03 to 10 per cent., preferably 1 to 3 per cent., of a dithiocarbamate of formula: <FORM:0711586/V/1> wherein R is a saturated or unsaturated alkyl, aryl or amino-substituted alkyl or aryl group, R1 is hydrogen or an alkyl, aralkyl or alkamine group, or R+R1 is N-cycloalkyl, and M is antimony, bismuth, cadmium, copper, lead, selenium, sodium, tin or zinc and n the valency of this metal.  The numerous examples of such dithiocarbamates include bismuth, copper, lead and zinc dimethyl, zinc and bismuth diethyl, zinc diisopropyl, zinc, antimony, cadmium selenium, sodium and tin dibutyl, zinc diamyl, zinc diisoamyl, zinc dioctyl, zinc octadecyl, zinc n-pentamethylene,, zinc diethylenetriamine, zinc phenyl ethyl and zinc dibenzyl dithiocarbamates.  According to examples, the rubber may be natural raw rubber, natural raw rubber with polyisobutylene of mol. wt. 80,000-120,000, a butadiene (76 per cent.)-styrene (24 per cent.) copolymer or devulcanized reclaim rubber, a mixture of Chilte, Massara and Venezuelan balatas, and the resin may be p-tert. amyl phenol-formaldehyde resin of m.pt. 85 DEG C, a polybetapinene of m.pt 70 DEG C. or 115 DEG C., hydrogenated rosin glyceride or gum rosin of m.pt. 80 DEG C., dehydrogenated rosin of m.pt. 75 DEG C., dehydrogenated rosin glyceride of m.pt. 80 DEG C. Other ingredients of the compositions may be a liquid or waxy plasticizer such as lanolin, mineral oil, paraffin wax of m.pt. 165 DEG C., a filler such as starch, zinc oxide, titanium dioxide, calcium carbonate, hydrated aluminum silicate, clay, talc, carbon black, and a standard anti-oxidant such as phenyl beta naphthylamine, butylated polyhydroxyphenol of m.pt above 150 DEG C., p-tert. amyl polyhydroxyphenol of m.pt. 150 DEG C.